5-aminolevulinic acid (hereinafter also referred to as “ALA”) is a type of natural amino acid comprised in vivo that exists widely in animals or plants or fungi, and is metabolized in cells as a common precursor of chlorophyll or heme. Although ALA, similarly to other porphyrin-related compounds, has the nature to selectively accumulate in tumor tissues, it does not itself possess light sensitivity, but becomes light sensitive protoporphyrin IX (hereinafter also referred to as “PpIX”) by being metabolized by a series of enzymes in the heme biosynthetic pathway in cells.
Research on 5-aminolevulinic acid—photodynamic therapy (hereinafter also referred to as “ALA-PDT”) or 5-aminolevulinic acid—photodynamic diagnosis (hereinafter “ALA-PDD”) that utilize the above nature of ALA and a metabolic product thereof PpIX has been brought forward (e.g. Patent Literature 1). Cancer therapy by ALA-PDT is a therapeutic method of treating cancer by administering ALA to a subject and irradiating light of a particular wavelength to the cancer tissue, is a therapeutic method that is minimally invasive and has less chance of leaving a therapeutic scar, and therefore has been gathering attention in recent years. ALA-PDD is a diagnostic method of determining the presence or absence of cancer tissue and the range of cancer tissue by administering ALA to a subject and irradiating light of a particular wavelength to the cancer tissue, is minimally invasive and has less side effects compared to prior diagnostic methods, and therefore has the advantage of having less burden on patients.
Further, it is known that a composition comprising ALA may be utilized for various applications such as prevention and alleviation of side effects of anticancer agents (Patent Literature 2), prevention and improvement of hangovers (Patent Literature 3), and prevention and improvement of cancerous anemia (Patent Literature 4).